NEW YORK (CBS, AP) -- A former convenience store worker confessed to luring 6-year-old Etan Patz from his school bus stop in 1979 and choking him to death in a basement, police said Thursday, ending a three-decades long investigation into one of the nation's most baffling missing-children cases.

In this 1979 photo provided by the New York City Police Department shows a missing child poster for Etan Patz. New York City Police and the FBI began digging up a New York basement Thursday, April 19, 2012 for the remains of the 6-year-old boy whose 1979 disappearance on his way to school drew helped launch a missing children's movement that put kids' faces on milk cartons

Pedro Hernandez, 51, of Maple Shade, N.J., was arrested on a murder charge after he told police he promised the boy a soda, took him to his store -- just blocks from Etan's lower Manhattan home -- and killed him there, Police Commissioner Raymond Kelly said.

Hernandez told police he put Etan's body in some trash about a block from the store, Kelly said, where it's possible it was picked up by sanitation crews. No body has been recovered, and Kelly said it's possible the remains would never be found.

Hernandez was questioned by police for more than three hours after he was picked up in New Jersey Wednesday, and gave police a signed confession, Kelly said. His motive was not yet clear.

It's not clear if he had an attorney; an arraignment was expected sometime Friday. No one answered the door at Hernandez' New Jersey home Thursday night.

"He was remorseful, and I think the detectives thought that it was a feeling of relief on his part" to confess, Kelly said. "We believe that this is the individual responsible for the crime."

The arrest is the first ever in the decades-old case that gave rise to the missing-children's movement and ushered in an era of anxiety about leaving children unsupervised. Etan's photo was one of the first of a missing child to appear on a milk carton. The anniversary of Etan's disappearance, which is Friday, was named National Missing Children's Day by presidential proclamation in 1983.

Detectives are often barraged with hoaxes, false leads and possible sightings around the anniversary of the boy's disappearance. But Kelly said they believed Hernandez's story because of specific details he gave to police.

Hernandez, then 19, had worked as a stock clerk at the store for about a month and wasn't questioned at the outset, Kelly said. But he later told relatives, as far back as 1981, that he had "done something bad" and killed an unnamed child in New York City, he said.

After a search of a basement near Patz' lower Manhattan home last month hurtled the case back into the news, a tipster pointed police to Hernandez. Kelly said the person wasn't a relative, but knew that Hernandez had said he had done a bad thing, he said.

Hernandez was known to police as being a worker at the convenience store -- a popular fixture in the neighborhood -- but was never questioned, though other people in the shop were.

He left his job days after Etan disappeared and moved to New Jersey, where he had relatives, Kelly said. Hernandez later worked in construction but has been collecting disability payments since a 1993 back injury, police said. He is married with a teenage daughter, he said.

Watch a video below of NYPD commissioner Ray Kelly at a news conference on the announcement of Pedro Hernandez's arrest:

The focus on Hernandez came after other leads arose and stalled, at one point taking investigators as far as Israel tracking reported sightings of the boy.

For most of the past decade, the investigation focused on Jose Ramos, a convicted child molester now in prison in Pennsylvania. He had been dating Etan's baby sitter. In 2000, authorities dug up Ramos' former basement in lower Manhattan, but nothing turned up.

Manhattan District Attorney Cyrus R. Vance Jr. announced in 2010 that his office was renewing the investigation into the case. A few weeks ago, investigators excavated another basement, down the street from the Patz apartment. The search found no human remains.

Recently, investigators questioned a 75-year-old Brooklyn handyman who in 1979 had a workspace in the basement that was excavated last month. The man, Othniel Miller, was not named as a suspect and denied any involvement. Miller's lawyer said there was no connection between Miller and Hernandez.

"There has been no law enforcement action taken or implicated against Mr. Miller as of yet. Mr. Miller is relieved by these developments, as he was not involved in any way with Etan Patz's disappearance," attorney Michael Farkas said.

Neighbors in Maple Shade, N.J., said Hernandez lived with his wife and a daughter who attends college. They expressed surprise Thursday night at the arrest.

"I knew the guy. He was not a problem. His family was great people," said Dan Wollick, 71, who rents an apartment in Hernandez' home ."He didn't bother anybody."

Sandy-haired Etan vanished while walking alone to his bus stop for the first time, two blocks from his home in New York's busy SoHo neighborhood, which was a working-class part of the city back then but is now a chic area of boutiques and galleries.

Etan's parents, Stan and Julie Patz, were reluctant to move or even change their phone number in case their son tried to reach out. They still live in the same apartment.

They did not return a call for comment Thursday. Lt. Christopher Zimmerman of the Missing Persons Squad said he'd spoken to Patz' parents.

"Mr. Patz was taken aback, a little surprised, and I would say overwhelmed to a degree," he said. "He had a few specific questions. He was a little surprised, but I think after everything Mr. Patz has gone through, he handled it very well."

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